The connections between the rotational transition cross sections in diatomic molecules

The collisions of diatomic (or linear) molecules with atomic particles are considered in the adiabatic (or infinite order sudden) approximation. All rotational transition cross sections are expressed via a small number of independent parameters in the general case when the collision is also accompanied by the electronic-vibrational transition in the molecule. In the simplest cases, the parameters are the cross sections of various transitions from the initial ground rotational state. Various angular momenta coupling schemes are considered in the initial and final electronic states of the molecule. The rotational transitions in bimolecular collisions are also discussed. The rotational transition cross sections in the homonuclear diatom with one nucleus substituted by its isotope are expressed in terms of the cross sections in the homonuclear molecule. The connections between the cross sections are similar to the expressions for radiational transition intensities since they do not depend on the interaction potential of the colliding partners. Due to their generality and simplicity the cross section connections will be useful in various problems of molecular collision physics and its applications.